https://www.youngju.dev/blog 천천히 올바르게. AI Researcher & DevOps Engineer Youngju's blog. GPU/CUDA, LLM, MLOps, Kubernetes AI workloads, and data engineering — plus mindset essays on confidence, routines, health, and sport psychology. ko fjvbn2003@gmail.com (Youngju Kim) fjvbn2003@gmail.com (Youngju Kim) Sat, 15 Aug 2026 00:00:00 GMT https://www.youngju.dev/blog/linux/2026-08-15-guide-git-undo.en https://www.youngju.dev/blog/linux/2026-08-15-guide-git-undo.en Maps the boundary between reset, revert, restore, reflog, and fsck by what can actually be recovered. Covers reflog expiry policy, when gc really deletes objects, force-push accidents, and worktree and submodule situations. Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) git버전관리복구운영협업명령어 https://www.youngju.dev/blog/linux/2026-08-15-guide-git-undo.ja https://www.youngju.dev/blog/linux/2026-08-15-guide-git-undo.ja reset、revert、restore、reflog、fsck の境界線を復元可能性という基準で整理します。reflog の期限切れポリシーと gc が実際にオブジェクトを削除するタイミング、強制プッシュ事故やワークツリー・サブモジュールの状況まで扱います。 Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) git버전관리복구운영협업명령어 https://www.youngju.dev/blog/linux/2026-08-15-guide-git-undo https://www.youngju.dev/blog/linux/2026-08-15-guide-git-undo reset, revert, restore, reflog, fsck의 경계선을 복구 가능성 기준으로 정리합니다. reflog 만료 정책과 gc가 언제 객체를 실제로 지우는지, 강제 푸시 사고와 워크트리·서브모듈 상황까지 다룹니다. Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) git버전관리복구운영협업명령어 https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-performance-tools.en https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-performance-tools.en Interprets the numbers printed by top, vmstat, iostat, pidstat, sar and perf one column at a time. Covers which tool answers which question, which values create optical illusions, and the order in which to choose a tool using the USE method. Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) 리눅스성능모니터링운영sysstat명령어 https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-performance-tools.ja https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-performance-tools.ja top、vmstat、iostat、pidstat、sar、perf が出力する数字を 1 列ずつ解釈します。どのツールがどの質問に答えるのか、どの値が錯覚を起こすのか、USE 方法論でツールを選ぶ順番までを整理しました。 Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) 리눅스성능모니터링운영sysstat명령어 https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-performance-tools https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-performance-tools top, vmstat, iostat, pidstat, sar, perf가 찍어 주는 숫자를 한 열씩 해석합니다. 어떤 도구가 어떤 질문에 답하는지, 어떤 값이 착시를 일으키는지, USE 방법론으로 도구를 고르는 순서까지 정리했습니다. Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) 리눅스성능모니터링운영sysstat명령어 https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-troubleshooting-commands.en https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-troubleshooting-commands.en The diagnostic commands to run, in order, from the moment someone tells you a server is misbehaving. uptime, top, free, df, iostat, ss, journalctl — which number in each output to read, and what that number rules out versus what it leaves standing. Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) 리눅스트러블슈팅운영장애대응명령어성능 https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-troubleshooting-commands.ja https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-troubleshooting-commands.ja サーバーの様子がおかしいと連絡を受けた瞬間から順番に実行する診断コマンドを整理します。uptime、top、free、df、iostat、ss、journalctlまで、各出力のどの数字を見るべきか、その数字が何を除外して何を残すのかを説明します。 Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) 리눅스트러블슈팅운영장애대응명령어성능 https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-troubleshooting-commands https://www.youngju.dev/blog/linux/2026-08-15-guide-linux-troubleshooting-commands 서버가 이상하다는 연락을 받은 순간부터 순서대로 실행하는 진단 명령어를 정리합니다. uptime, top, free, df, iostat, ss, journalctl까지 각 출력의 어느 숫자를 봐야 하는지, 그 숫자가 무엇을 배제하고 무엇을 남기는지 설명합니다. Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) 리눅스트러블슈팅운영장애대응명령어성능 https://www.youngju.dev/blog/linux/2026-08-15-guide-process-and-signals.en https://www.youngju.dev/blog/linux/2026-08-15-guide-process-and-signals.en Signal numbers and default actions, the difference between SIGTERM and SIGKILL, zombies and orphans, process groups and sessions, nohup and setsid, and how to design a graceful shutdown. Traces the cause of a process that refuses to die, one layer at a time. Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) 리눅스프로세스시그널운영커널명령어 https://www.youngju.dev/blog/linux/2026-08-15-guide-process-and-signals.ja https://www.youngju.dev/blog/linux/2026-08-15-guide-process-and-signals.ja シグナル番号と既定動作、SIGTERM と SIGKILL の違い、ゾンビと孤児、プロセスグループとセッション、nohup と setsid、そしてグレースフルシャットダウンを設計する方法までを整理します。死なないプロセスの原因を階層ごとに追跡します。 Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) 리눅스프로세스시그널운영커널명령어 https://www.youngju.dev/blog/linux/2026-08-15-guide-process-and-signals https://www.youngju.dev/blog/linux/2026-08-15-guide-process-and-signals 시그널 번호와 기본 동작, SIGTERM과 SIGKILL의 차이, 좀비와 고아, 프로세스 그룹과 세션, nohup과 setsid, 그리고 우아한 종료를 설계하는 방법까지 정리합니다. 죽지 않는 프로세스의 원인을 계층별로 추적합니다. Sat, 15 Aug 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) 리눅스프로세스시그널운영커널명령어